The following prior art references relate to various structures for removing heat from solder bonded semiconductor devices. U.S. Pat. No. 3,993,123 discloses a semiconductor package in which a movable heat conductive piston is placed in contact with the back side of a solder bonded semiconductor device to conduct heat away from the device to a cooling plate. U.S. Pat. Nos. 4,034,468 and 4,081,825 both disclose semiconductor packages wherein a low melting point solder is provided in contact with the back side of a solder bonded device and with the module cap to remove heat from the device. U.S. Pat. No. 4,156,458 discloses a cooling arrangement including a flexible heat conductive metallic foil bundle extending between the back side of a device and the heat sink. IBM Technical Disclosure Bulletin Vol. 21 No. 3 Aug. 1978 P. 1141 discloses a thermal shunt element disposed between a solder bonded semiconductor device and a module cap comprised of a rectangular center portion and a pair of divergent wings that contact the cap. IBM TDB Vol. 20 No. 6 Nov. 1977 P. 2214 and U.S. Pat. No. 4,156,458 issued May 29, 1979 disclose a plurality of preform sheets of aluminum foil nested together and disposed between solder bonded semiconductor devices and a housing to remove heat from the devices. IBM TDB Vol. 19 No. 12 May 1977 P. 4683 discloses a thermal conduction bridge element between a solder bonded semiconductor device and a cap which features a plurality of interleaved relatively slidable fins. Application Ser. No. 249,262, filed Mar. 30, 1981, assigned to the same assignee as this application, discloses a thermal bridge for conducting heat from a device to the cover which includes a relatively thick metal sheet provided with cuts that define at least one tab element.
The invention is an improved cooling element adapted to be positioned between a solder bonded semiconductor device and a module cap or cold plate to form a heat conduction bridge between the device and cap or cold plate. The thermal bridge element is a bulged disk of resilient heat conductive material, typically a copper or silver alloy containing a small amount of material to make the material more spring-like, the disk provided with a first plurality of spaced radial slots emanating from a common central point and terminating short of the outside edge, a second plurality of spaced radial slots located between the first plurality of radial slots in alternating relation and extending from the edge inwardly terminating short of the center of the disk. The disk is preferably provided with a low melting coating such as lead, tin, indium or a low melting solder. The combination of inwardly and outwardly radiating slots permits the use of a much thicker disk, capable of effectively and efficiently conducting heat while yet retaining the ability to flex without imposing destructive stresses on the device.